There is a "cheap repair" kit for the J30, but sadly not for the Q45.
I had a simliar problem and manged to push the lagging side with my hand in the "tilt flap" while the swicth was in close mode and got the sunroof closed with some effort.
There are intruction in the service manual but it's not DIY friendly.
A freind of mine whose skills ar higher than mine tried to follow those intruction to fix the roof but in the reulst we just bent a rail

and went from "just a brokewn cable" to needing a new assembly ( Ch-ching $2000+ installed at dealer, $1400 at T3 w/ used assembly).
Not only that it was now completly impossible to close as one side was out-of syn with the other so I HAD to have the work done and have it done right away.
Depending on your budget this is my advice:
If its healthy, go to dealer or nearest highly competent service facilty and have it done and done right and enjoy your sunrrof again.. ORClose it by hand pushing the lagging side with some strenght until it completely and and then leave it alone over the approaching winter until u have some $$ saved .
Fred...
